/**
 * Copyright (c) 2011-2023, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jfinal.template.source;

import java.io.File;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import com.jfinal.template.EngineConfig;

/**
 * ClassPathSource 用于从 class path 以及 jar 包之中加载模板内容
 *
 * <pre>
 * 注意：
 * 1：如果被加载的文件是 class path 中的普通文件，则该文件支持热加载
 *
 * 2：如果被加载的文件处于 jar 包之中，则该文件不支持热加载，jar 包之中的文件在运行时通常不会被修改
 *    在极少数情况下如果需要对 jar 包之中的模板文件进行热加载，可以通过继承 ClassPathSource
 *    的方式进行扩展
 *
 * 3：JFinal Template Engine 开启热加载需要配置 engine.setDevMode(true)
 * </pre>
 */
public class ClassPathSource implements ISource {

    protected String finalFileName;
    protected String fileName;
    protected String encoding;

    protected boolean isInJar;
    protected long lastModified;
    protected ClassLoader classLoader;
    protected URL url;

    public ClassPathSource(String fileName) {
        this(null, fileName, EngineConfig.DEFAULT_ENCODING);
    }

    public ClassPathSource(String baseTemplatePath, String fileName) {
        this(baseTemplatePath, fileName, EngineConfig.DEFAULT_ENCODING);
    }

    public ClassPathSource(String baseTemplatePath, String fileName, String encoding) {
        this.finalFileName = buildFinalFileName(baseTemplatePath, fileName);
        this.fileName = fileName;
        this.encoding= encoding;
        this.classLoader = getClassLoader();
        this.url = classLoader.getResource(finalFileName);
        if (url == null) {
            throw new IllegalArgumentException("File not found in CLASSPATH or JAR : \"" + finalFileName + "\"");
        }

        processIsInJarAndlastModified();
    }

    protected void processIsInJarAndlastModified() {
        if ("file".equalsIgnoreCase(url.getProtocol())) {
            isInJar = false;
            lastModified = new File(url.getFile()).lastModified();
        } else {
            isInJar = true;
            lastModified = -1;
        }
    }

    protected ClassLoader getClassLoader() {
        ClassLoader ret = Thread.currentThread().getContextClassLoader();
        return ret != null ? ret : getClass().getClassLoader();
    }

    protected String buildFinalFileName(String baseTemplatePath, String fileName) {
        String finalFileName;
        if (baseTemplatePath != null) {
            char firstChar = fileName.charAt(0);
            if (firstChar == '/' || firstChar == '\\') {
                finalFileName = baseTemplatePath + fileName;
            } else {
                finalFileName = baseTemplatePath + "/" + fileName;
            }
        } else {
            finalFileName = fileName;
        }

        if (finalFileName.charAt(0) == '/') {
            finalFileName = finalFileName.substring(1);
        }

        return finalFileName;
    }

    public String getCacheKey() {
        return fileName;
    }

    public String getEncoding() {
        return encoding;
    }

    protected long getLastModified() {
        return new File(url.getFile()).lastModified();
    }

    /**
     * 模板文件在 jar 包文件之内则不支持热加载
     */
    public boolean isModified() {
        return isInJar ? false : lastModified != getLastModified();
    }

    public StringBuilder getContent() {
        // 与 FileSorce 不同，ClassPathSource 在构造方法中已经初始化了 lastModified
        // 下面的代码可以去掉，在此仅为了避免继承类忘了在构造中初始化 lastModified 的防卫式代码
        if (!isInJar) {		// 如果模板文件不在 jar 包文件之中，则需要更新 lastModified 值
            lastModified = getLastModified();
        }

        InputStream inputStream = classLoader.getResourceAsStream(finalFileName);
        if (inputStream == null) {
            throw new RuntimeException("File not found : \"" + finalFileName + "\"");
        }

        return loadFile(inputStream, encoding);
    }

    public static StringBuilder loadFile(InputStream inputStream, String encoding) {
        try (InputStreamReader isr = new InputStreamReader(inputStream, encoding)) {
            StringBuilder ret = new StringBuilder();
            char[] buf = new char[1024];
            for (int num; (num = isr.read(buf, 0, buf.length)) != -1;) {
                ret.append(buf, 0, num);
            }
            return ret;

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("In Jar File: ").append(isInJar).append("\n");
        sb.append("File name: ").append(fileName).append("\n");
        sb.append("Final file name: ").append(finalFileName).append("\n");
        sb.append("Last modified: ").append(lastModified).append("\n");
        return sb.toString();
    }
}


/*
    protected File getFile(URL url) {
        try {
            // return new File(url.toURI().getSchemeSpecificPart());
            return new File(url.toURI());
        } catch (URISyntaxException ex) {
            // Fallback for URLs that are not valid URIs (should hardly ever happen).
            return new File(url.getFile());
        }
    }
*/

